Historically, research on BCAAs has been conducted to determine its effects on central fatigue, peripheral fatigue, and most recently its effects on cell-signaling properties leading to an increase in protein synthesis. In relation to high intensity activities, such as resistance exercise, few published data exist investigating the short-term effects of BCAA supplementation on resistance exercise performance.
PURPOSE: To determine the effect of BCAA supplementation on total workout volume achieved during an acute bout of lower-body resistance exercise in comparison to a placebo.
METHODS: In a randomized, double blind, placebo controlled design, 14 recreationally active males were divided into a BCAA (n = 7) and a placebo (n = 7) group (BCAA = 25.6 ± 4.7 yrs, 180.7 ± 6.6cm, 89.1 ± 10.7 kg; placebo = 20.0 ± 0.8 yrs, 174.5 ± 6.2cm, 80.1 ± 11.6 kg). The participants ingested either 80 mg/kg of BCAAs divided into 2 equal doses or a similar tasting placebo in conjunction with a lower body resistance exercise (RE) bout. The RE bout consisted of 4 sets of leg press followed by 4 sets of knee extension at 80% 1RM to failure. Only those participants who were able to achieve a minimum of 8 repetitions at 80% of 1RM on every set were included in the analysis. However, all participants were required to attain volitional fatigue. Rest periods between sets and exercises were approximately 150 seconds. Supplementation was administered 30 minutes prior and immediately before RE. Total lower-body workout volume between groups was analyzed via an independent samples t-test using SPSS for Windows version 15.0.
RESULTS: Data are reported as means ± standard deviation. Total lower-body workout volume for the BCAA and placebo groups was 18,754 ± 1,573 kg and 18,260 ± 6,519 kg, respectively. Independent samples t-test revealed that there were no significant differences between the two groups (t(12) =.169, p =.869).
CONCLUSION: At a dosage of 80 mg/kg of bodyweight, it appears that BCAA supplementation does not increase total lower-body workout volume at an intensity of 80% 1RM to volitional exhaustion during an acute bout of resistance exercise.